def hawkI_fov(xc,yc,colour='b'):
    ax = pl.gca()
    pixscale = 0.1064/3600.    # deg per pixel
    q1 = -2163, -2164
    q2 = 37.5, -2161.5
    q3 = +42,+28
    q4 = -2158,+25.5
    #q1,q2,q3,q4 = ((np.array(q)+1024)*pixscale for q in (q1,q2,q3,q4))
    for q in q1,q2,q3,q4:
        x = xc+q[0], xc+q[0], xc+q[0]+2048,xc+q[0]+2048
        y = yc+q[1], yc+q[1]+2048, yc+q[1]+2048, yc+q[1]
        ax.fill(x,y,colour,alpha=0.2)    
    ax.axis('equal')
    pl.show()
    
    
#     Quadrant CRPIX1 CRPIX2
# Q1         2163    2164
# Q2         -37.5 2161.5
# Q3           -42    -28
# Q4         2158   -25.5


if 0:
    pl.cla()
    offset = 2000            # 212.8 arsec
    hawkI_fov(0,0,colour='b')
    hawkI_fov(offset,0,colour='b')
    hawkI_fov(0,offset,colour='b')
    hawkI_fov(offset,offset,colour='b')
    
    
